| Project/Area Number |
08650560
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
構造工学・地震工学
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| Research Institution | Tohoku University (1997)
Tokai University (1996) |
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Principal Investigator |
KITAHARA Michihiro Tohoku University, Dept.of Civil Engineering, Professor, 大学院・工学研究科, 教授 (60135522)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1996: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Scattering cross-section / Attenuation / Crack / Ultrasonics / Elastodynamic scattering |
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| Research Abstract |
The results of the study are summarized as follows.
1.The boundary integral equation to determine crack opening displacements was formulated for scattering problems of a crack in three dimensional elastic solids. The quarter point elements were introduced for the crack tip and the regularization was performed for the hyper singular kernel of the boundary integral equation.
2.Far-field expressions of longitudinal and transverse scattering amplitudes were obtained from the three-dimensional elastodynamic Green's function. Then the expression of elastodynamic scattering cross-sections was formulated from the far-field scattering amplitudes.
3.The angular distributions of differential scattering cross-sections were numerically calculated and the frequency characteristics of the elastodynamic scattering cross-section were investigated. It was found that the longitudinal part of the differential scattering cross-section is localized to the propagation direction of the incident wave when the frequency increases. The total scattering cross section has a peak when the wavelength of the incident wave becomes the order of crack diameter.
4.The relation of elastodynamic scattering cross-section, attenuation and crack density was obtained from the assumption of the dilute distribution of cracks in structural components. It was proposed to estimate the crack density by measuring the attenuation in damaged components.
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